**3. Results and discussion**

**Table 1** shows the CIELab coordinates of the sparkling wines. As expected, the blue-yellow CIELab component (b\*) clearly increased as the aging time increased. These data confirm a fact that is well known by winemakers: the intensity of the yellow color progressively increases over time. **Table 1** also shows the foaming properties of these sparkling wines. Both the maximal height of the foam (foamability [HM]) and the stable height of the foam (foam stability [HS]) showed a similar tendency, they increased between the first and second year of aging and decreased progressively afterward.

**Figure 3** shows the polysaccharide concentration of the sparkling wines of the nine consecutive vintages. In general, no clear trend was detected either in the total concentration of polysaccharides or in any of its different fractions of different molecular weight. This lack of tendency seems to contradict what should be expected from yeast autolysis, as it should theoretically increase its concentration over time. Nevertheless, other authors also found no clear trend in the evolution of the polysaccharide fraction during the aging of sparkling wines on lees [13, 30, 31].

A possible explanation for this lack of trend maybe that polysaccharides are simultaneously released and removed from the media. Yeast autolysis may be a source of polysaccharides and mannoproteins [32]. However, polysaccharides can also disappear by precipitation [13], absorption by the riddling agents [33] and enzymatic degradation [30]. In addition, the variability among vintages may overlap making it very difficult to detect any tendency.

**Figure 4** shows the protein concentration of the sparkling wines of the various vintages. Similar to what happened with polysaccharides, no clear trend was observed throughout aging time, neither in the concentration of total protein nor in any of its fractions of different molecular weight. Once again, these results may appear to contradict what is expected from yeast autolysis. However, other authors have also reported a similar erratic behavior [34–36].

Similar to what happened with polysaccharides, this lack of tendency may be related to a balance between the proteins released from yeast autolysis and those that disappear due to bentonite absorption and enzymatic degradation [9, 34, 35, 37]. Furthermore, the variability in the protein concentrations of each vintage can make it difficult to conclude.

Since no tendency was observed for either polysaccharides or proteins, it was decided to study the release of these macromolecules from the lees using a different


**Table 1.**

*CIELAB coordinates and foaming properties of the sparkling wines of different aging time.*
